Car runs rough at idle

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Jul 9, 2009
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austin,tx
This is the code I get. P0352 Ignition Coil Primary B / Secondary Circuit Malfunction, all the cops(coil on plugs)are new about 8 months old and the spark plugs were replaced a year ago. I starts fine, its when its idling at a stop light or whatever it will go rough. But when I start driving it will drive rough for a little bit, then snap out of it and drive fine and have full power again. Any idea's? thanks
 
When the engine starts to idle rough pull over to a stop, leave the engine running and place a cloth up to the tail pipe. Don't completly close the pipe off but leave a slight gap between the pipe and cloth. If there is a miss it will suck the cloth up to the pipe with every miss fire. Ignition problem. It will make a pop pop sound with the miss. If no miss then look else where for your idle problem. Injector etc.
 
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He already states that there is a miss.
Why check for it at the tailpipe? - that is silly.

Can you quickly disconnect power to each coil when it is misfiring?
A good coil/plug will show even worse, and a bad one no change.

Even though an ignition code is being thrown, it may be a vacuum leak or fuel delivery problem. Maybe even an EGR thing.
Sometimes computers give codes for left handed reasons.
 
I think that means there is a problem at coil number 2 or b. What kind of plugs and coils did you use as replacements? You might want to check the wiring harness to that coil.
 
I got the coils off of ebay. Non oem all 8 for $70 and the plugs are standard motorcarft plugs. I will check the wiring harness and see what I come up with.
 
Also if possible I think you could swap coils and if the problem moves with the coil you know that's it. Or maybe you could check the coils primary and secondary resistance against specs.
 
Quote:
Maybe even an EGR thing.


That would produce a rough idle that totally evaporated in the upper power levels.

If you have a vacuum actuated EGR, then pull the hose off of the supply side and apply vacuum (suck on it). If the engine stumbles ..then it's probably closed like it should be. If nothing happens then it's probably stuck.
 
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